Motor-controller.



T. E. BARNUM.

MOTOR CONTROLLER.

APPLICATION FILED JUNE 1, 1909.

Patented Dec. 22, 1914.

UNITE sn'rns rarer FFICE.

THOMAS E. BAR-NUM, 0F MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLER-HAMMER MFG. (30., OF MILWAUKEE, WISCONSIN, A CORPORATION OF WIS- CONSIN.

MOTOR-CONTROLLER.

memes.

Application filed June 1, 1909.

To all whom it may concern Be it known that I, THOMAS E. BARNUM, acitizen of the United States, residing at Milwaukee, in the county ofMilwaukee and State of Wisconsin, have invented new and usefulImprovements in Motor-Controllers, of which the following is a full,clear, concise, and exact description, referencebeing had to theaccompanying drawing, forming a part of this specification.

My invention relates to improvements of controllers fOl electric motorsand more particularly to controllers for motors havingshunt fieldwindings.

One object of my invention is to provide means adapted to be controlledfrom a distant point, to open and close the circuits of both themotorarmature and shunt field winding at will.

A further object of my invention is to provide means for establishing adynamic braking circuit for the motor, and insuring energization of theshunt field winding during the braking period.

A still further object of my invention is to provide means for insuringenergization of the shunt field winding of the motor when its armaturecircuit is closed.

Various other objects and advantages of my invention will be hereinafterfully and clearly setforth.

In order to more clearly disclose the nature of my invention, I shalldescribe the system of control diagrammatically illustrated inthe,acompanying drawing. The system of control which .I have shownmerely illustrates the general principles of my invention and simplyshows diagrammatically one form in which it may be embodied. I have madeno attempt in the drawing to illustrate all of the apparatus which wouldbe used in my controller in practice, but have eliminated. many devicesthat would be used, in order to simplify the illustration anddescription of my invention. Of course, my invention is susceptible ofvarious modifications.

The controller illustrated in the drawin includes a'main switch 1, anauxiliary main.

Specification of Letters Patent.

Patented Dec. 22, 1914. Serial No. 499,422.

vention are equally as applicable to compound motors. The device 3 inthe present instance is merely employed for controlling a startingresistance 6 in the armature circuit of the motor. This device comprisesa pivoted element 7, having an operating.

winding 7 adapted to move the same over a series of contacts 8 togradually remove the resistance 6 from circuit. 'It should beunderstood, however, that I may use an automatic speed controllingdevice in conjunction with the automatic starting device, or that Imight employ a combined starting and speed regulating device in lieu ofthe starting device illustrated. The plunger of the operating winding Y-is preferably provided with a tail rod carrying a contact disk. 9adapted to engage a pair of stationary contacts when the controllingelement 7 is in initial position. I'also preferably provide the mainswitch 1 with an auxiliary contact disk 10 adapted to engage a pair ofstationary contacts when the main switch .1 is closed. The purpose ofthese auxiliary contact disks will be hereinafter clearly and fully setforth.

The dynamic braking switch 4:, as will be hereinafter set forth, isadapted to complete ing windings of the several switches to start andstop the motor, I have shown a master switch 13. This master switch may,in practice, be of any preferred type and arranged at. a distance fromthe several switches. as illustrated, themaster switch 13 comprises apivoted element 14 provided. with contact brushes 15 and 16. When themember It is moved to the left frominitial position, the brush 16 firstengages a contact segment 17 and then the brush 15 en-' gages a contactsegment 18. The motor and the operating windings of the severalconductor 22, through the arm 14 of the switches are supplied withcurrent from main lines and 21.

I shall now describe the operation of the controller, at the same timeclearly explaining the circuit connections therefor. Assuming the masterswitch and the several electroresponsive switches to be in the positionillustrated, no current will flow through either the motor armature orshunt field winding. To start the motor, the movable element 14 of themaster switch should be moved to the left, thus-bringing the contactbrush 16, carried thereby, into engagement with the contact segment 17This completes a circuit from main line 20 by master switch, to contactsegment 17, by conductor 23 through the operating winding 1 of mainswitch 1, by conductors 24, 25 and 26 to main line 21. This completesthe circuit'of the winding 1?, which there upon responds and closes theswitch 1. Closure of the switch 1, however, does not immediately closethe motor circuit, inasmuch as the. motor circuit is interrupted at theswitch 2. However, upon closure of switch 1, contact disk 10, operatedthereby,

" ary contacts.

is moved into engagement with its station- This closes a circuit frommain line 20 by conductor 27, through the operating winding 2 of theauxiliary switch 2, by conductor 28 through the auxiliary contact disk10, 'to conductor 25,

and thence back to the negative side of the main line. The winding 2then responds, thereby closing the switch 2. Closure of the switch 2completes both the armature circuit and the shunt field circuit of themotor. The latter may be traced from conductor 27, through switch 2, byconductor 29, through the shunt field winding F, by

conductor 30 to the negative side of the main line. The armaturecircuit'ma'y be traced from conductor 27, through the switch 2, byconductor 31, through switch 1, by conductor 32, through the motorarmature A, by conductors 33 and 84, through all of the startingresistance 6, thence through the controlling elenient 7 to the negativeside of the main line. The motor will thereupon start with all of thestarting resistance in circuit. It should here be noted that 'with thearrangement which I have provided, it is impossible for the armaturecircuit to be completed until the circuit of the shunt fieldwinding isalso com pic-ted. If such provision was not made, the armature might beenergized without energizing the shunt field winding. This as is wellknown, establishes a dangerous condition in the motor. To bring themotor up to normal speed, the member 14of the master switch should bemoved so as to cause the brush 15 to engage a contact segment 18. Thiscompletes a circuit from the member 14 to contact segment 18, thence byconductor 35, through the operating winding 7 a of the starting deviceto the negative side of the main line. The winding 7 being thusenergized draws up the controlling member 7, thereby removing theresistance from the armature circuit. When all of the resistance 6 hasbeen removed from circuit, the motor will operate at normal speed.

As has been previously set forth, the device 3 might be providedtocontrol a regulating] resistance instead of a starting resistance. Themotor having now been brought up to normal speed, will continue tooperate until the controlling member of the master switch is movedtoward initial position. Upon the brush 15 leaving contact segment 18,the circuit of the winding 7 is opened, thereby releasing thecontrolling element 7. which then descends, to gradually reinsert theresistance 6'in the armature circuit. This, of

course, slows down the motor. WVhen the member 7 reaches the initialposition, the auxiliary contact 9 of the device. 3 is brought intoengagement with its stationary contacts. The contact disk 9 thereuponconnects the operating winding 4 of the dynamic braking switch directlyacross the terminals of the motor armature. The circuit of this windingmay be traced from one terminal of the motor armature by conductors 33and 37 through the contact disk 9, by conductor 38, through the winding4, by conductors 39 and 32 to the opposite terminal of the motorarmature. The winding 4 will thus be rendered. responsive to the C. E.M. F. ofthe motor armature, and,

when energized, closes the switch 4. C10- sure of the switch 4 completesa closed loop across the terminals of the motor armature which may betraced from one terminal thereof by conductor 83, through the resistance11, switch 4, by conductor 32 to the opposite terminal of the motorarmature. The establishment of this circuit diverts part ,of the flow ofcurrent from the motor armature as long as the same is connected to themain line, and at the same time constitutes a dynamic braking circuit ifthe motor is driven under the impetus acquired by its load. Of course,after the dynamic opens the armature circuit and wouldIht the same time,open the circuit of the wind ing 2 of the auxiliary switch 2, but forthe fact that upon closure of the dynamic braking switch &, the contactdisk 12, operated cause the motor armature to be disconnected from thesupply source while the shunt field winding, will be maintainedenergized. As soon as these conditions are established, the motor willbe quickly brought to rest under the influence of the dynamic brakingcurrent generated thereby. 3f course, as the motor armature slows down,the current generated thereby decreases until finally insufficientcurrent is generated to maintain the winding of the dynamic brakingswitch energized. The switch l thereupon opens, and, immediately uponopening, moves the auxiliary contact disk 12 "out of engagement with-itsstationary contact. This, of course, interrupts the circuit 0 theoperating winding of the auxiliary main switch 2, which thereupon opensto disconnect the shunt field winding from the supply source. -Hence,when the motor comes to rest, it is completely disconnected from thesupply source. Of course, if after being slowed down by the reinsertionoi"- the startingresistance, the motor does not gen erate a; sufilcien tL1. E. M. F. to cause the operating winding of the dynamic brakingswitch to respond, then, as soon as the master switch is moved toinitial position, both the "main switch 1 and the auxiliary switch 2will "open, thereby interrupting the circuits of both theunotorarmatureand shunt field winding. I

\Vhile {have shown neans for opening the circuit of the shunt fieldwinding of the motor I might utilizethe switch 2 for weal:- ening theshunt field without interrupting its circuit if desired, Accordingly inspcaking of disconnecting the shunt field winding from circuit Icontemplate either weakening the shunt field winding or opening thecircuit thereoi whicheuer may be preferred.

Having thus described invention, what I claim as new and desire tosecure by Letters Patent, is

1. in a controller for an electric motor having a shunt field winding,rcombina- ,tion,'means for automatically varying; the

connections of the shunt field oi? the motor upon starting and stoppingand means for establishing a dynamic braking circuit to stop the motor,said first mentioned means insuring a strong shunt field upon initialclosure of the circuit of the motor armature in starting the motor andalso during the dynamic braking period. P

2. a controller for an electric motor having a shunt field winning, incombination, electroresponsi e means for varying the connections of theshunt field of the motor upon starting and stopping and means forestablishing, a dynamic braking circuit for the motor, saidelectr'oresponsive means insuring a strong shunt field upon initialclosure 0:1"; the circuit of the motor armature in starting and alsoduring the dynamic braking period.

3. In a controller for an electric motor having a shunt field winding,in combination, ,clectroresponsive means for Varying the connections ofthe shunt field of the motor in starting and stopping" and positivelyinsuring a strong field in starting and electroresponsive means forestablishing a dynamic braking circuit for the motor and controllingsaid first mentioned means to insure a strong field during the dynamicbraking period. v

4. in a controller for electric motors, in combination, anelcctroresponsive switch for controlling -'th'e continuity of thecircuit of the shunt field winding of the motor, means for controllingthe circuit of the operating winding of said switch, means forestablishing a dynamic braking circuit for the motor, and automaticmeans for establishing a maintaining circuit for the ,operating windingof said switch, independent of said controlling means, upon theestablishment of the dynamic braking circuit.

5. in a controller for electric motors, in combination, meanscontrollable from a distant point for controlling both the armaturecircuit and the shunt field circuit of the motor, said means tending toopen the shunt field circuit upon the opening of the armature circuit,and means for, establishing a dynamic braking circuit for the motor andmaintaining the shunt field winding of the motor energised after thearmature circuit has been opened.

6. in controller for electric motors, in

combination, means controllable from a distant point for controllin boththe armature circuit and the shunt neld circuit of the motor, said meanstending to open the shunt field circuit upon the opening of the armaturecircuit, and means for establishing a dynamic braking circuit for themotor and n'iaintaininn the shunt field winding of the motor energizedafter the armature circuit ha been opened for dynamic braking and thenautomatically disconnecting the same from circuit. i

in a controlle or electric motors, in combination, a pair orelectrorcsponsive switches for controlling the armature cirfieldcontrolling switch tending to open upon the opening of the other switch,and means for establishing a dynamic braking circuit for the motor andfor establishing a maintaining circuit for the operating winding of thefield controlling switch to retain the same clo'sed'after the motorarmature has been disconnected from circuit, said means being arrangedto interrupt said maintaining, circuit to permit said field controllingswitch to open when the motor has been .brought to rest.

9. In a controller for electric motors, in combination, anelectroresponsive switch for controlling the circuit of the shunt fieldwinding of the motor, an elect-roresponsive switch for establishing adynamic braking circuit for the motor, said braking switch having anoperating winding adapted to be connected across the terminals of themotor armature to respond to the counter electromotive force thereof,and a switch operable with said braking switch for establishing amaintaining circuit for the shunt field controlling switch during thedynamic braking period.

10. In a controller for electric motors, in

combination, an electroresponsive switch for establishing a dynamicbraking circuit for the :notor, means controllable from a distant pointfor slowing down the motor and then automatically connecting theoperating winding of said switch across the terminals of the motorarmature, an electroresponsive switch for controlling the circuit of theshunt field winding of the motor and tending to disconnect the shuntfield winding from circuit'when the armature is disconnected fromcircuit, and a switch operable with said dynamic braking switch formaintaining said field controlling switch energized during the dynamicbraking period.

11. In a controller for electric motors, in combination,electroresponsive switches for controlling both the armature circuit andthe shunt field circuit of the motor, electroresponsive means forestablishing a dynamic braking circuit for the motor, a master switchfor controlling said switches and said means, and means automaticallyoperated upon the establishment of the dynamic brakmerges ing circuitfor rendering said master switch ineffective to cause the fieldcontrollmg switch to disconnect the shunt field Winding from circuit.

12. In a controller for electric motors, in combination,electroresponsive switches for controlling both the armature circuit andthe shunt field circuit of the motor, electroresponsive means forestablishing a dynamic braking circuit for the motor, a master switchfor controlling said switches and said means, and means automaticallyoperated upon the establishment of the dynamic braking circuit forrendering said master switch ineffective to cause the field controllingswitch to disconnect the shunt field winding from circuit, said lastmentioned means tending to cause the deenergization of the fieldcontrolling switch to open the shunt field circuit when the motor isbrought to rest.

13. In a controller for electric motors, in combination, meanscontrolling the armature circuit, and meanscontrolling the shunt fieldcircuit, both of said means being controllable from a distant point,said first mentioned means being inefiective to close the armaturecircuit until said second mentioned means has been operated to close theshunt field circuit of the motor.

14. In a controller for electric motors, in combination, a pair ofswitches controllable from a distant point, both of said switches beingincluded in the armature circuit of the motor, and one of said switchesbeing included in the shunt field circuit thereof,

either of said switches being adapted to disconnect the motor armaturefrom circuit.

15.-In a controller for electric motors, in

combination,. an electroresponsive main switch, and an.electroresponsive auxiliary main switch, both of said switches beingincluded in the armature circuit, and said auxiliary switch beingincluded in the shuntfield circuit of the motor.

16. In a controller for electric motors, in combination, anelectroresponsive main switch, and an electroresponsive auxiliary mainswitch, both of said switches being included in the armature circuit,and said auxiliary switch being included 1n the shunt field circuit ofthe motor, and a switch operable with said main switch for controllingcuit and rendering the disconnectionof theshunt field winding subject tocontrol by said motor.

18. The combination with a motor having a shunt field Winding, of meansfor auto- .matically disconnecting the field winding from circuit whenthe motor is stopped and means for automatically closing and opening adynamic braking circuit for the motor, said first mentioned meansinsuring the retention of the shunt field winding in circuit until saidsecondmentioned means operates to open said dynamic braking circuit.

19. .In a controller for a motor having a shunt field Winding, incombination, means for automatically closing and opening a dynamicbraking circuit for the motor, means for automatically disconnecting theshunt field Winding of the motor from circuit when the motor is stopped,said means being interlocked to prevent operation of said secondmentioned means to disconnect the shunt field Winding from circuitexcept When said first mentioned means is in position to open saiddynamic braking circuit.

20. The combination With-a motor having a shunt field windingyof meanscontrollable from a distant point for controlling the continuity of theshunt field circuit, said means insuring disconnection of the motorarmature from circuit upon opening the shunt field circuit and insuringenergization of the shunt field Winding upon closure of the armaturecircuit.

21. The combination with a motor having a shunt field Winding, of meanscontrollable from a distant point for controlling the continuity of theshunt field circuit, said means insuring disconnection of the motorarmature from circuit upon opening the shunt field circuit and insuringenergization of the shunt field Winding upon closure of the armaturecircuit, and means controlling said first mentioned means to maintain'theshunt field Winding energized untilthe motor is substantiallybrought to rest and then automatically disconnecting the shunt fieldwinding from circuit.

In Witness whereof, I have hereunto subscribed my name in the presenceof two witnesses.

THOMAS E. BARNUM.

Witnesses:

FRANK H. HUBBARD, WALTER E. SARGENT.

